This invention relates to substantially optically transparent articles such as lenses having a wear-resistant surface formed thereon. Methods of making the same are also disclosed.
There are numerous methods for coating substrates to improve their performance, e.g., lifetime abrasion wear resistance. For example, many commercial plastic ophthalmic and sunglass lenses are coated with either organic acrylate polymer coatings or polysiloxane polymer coatings. Although these polymer coatings offer a significant improvement in abrasion resistance relative to the uncoated plastic lens, the perceived abrasion of the coated plastic lenses compared to glass is still poor. Inorganic hardcoatings deposited directly on the article have also been employed as protective layers to improve the abrasion resistance. However, these coatings have performance problems. Hardcoatings subjected to thermal and mechanical stresses may crack as a stress release mechanism when the article is subjected to various heating/cooling cycles. Wet adhesion of these films is poor, exposure to hot and cold moisture cause these films to delaminate from the substrate.
U.S. Pat. No. 5,476,717 to Floch describes an antireflective material comprising an organic or inorganic substrate, an adhesion promoter layer, an antireflection coating formed from colloids of silica in a siloxane binder; a silazane coupling layer, and an outer antiabrasion layer formed by the solvent deposition of a fluorinated polymer (particularly the polytetrafluoroethylene derivative known as TEFLON AF(copyright). The antiabrasion layer relies solely on the antifriction properties of the PTFE polymer, and is not itself resistant to gouging or scratching by forcefully applied abrasive particles which penetrate into the antiabrasion layer.
In accordance with the foregoing, a first aspect of the present invention is a substantially optically transparent article having a wear-resistant surface. The article comprises: a substantially optically transparent polymeric substrate having a surface portion, and having a hard antiabrasive interconnecting layer formed on the surface portion. A lubricious hydrophobic coating layer is bonded to the interconnecting layer, with the hard antiabrasive interconnecting layer and the lubricious hydrophobic coating layer together forming the wear-resistant surface. The lubricious hydrophobic coating layer preferably is formed of a hydrophobic organic lubricant selected from the group consisting of fluorocarbons, fatty acids, and fatty acid esters.
In a preferred embodiment of the foregoing:
(a) the substrate comprises a material selected from the group consisting of polycarbonate, poly (2,2xe2x80x2-dihydroxyphenylpropane)carbonate, polydiethyleneglycol bis(allyl carbonate), polyacrylate, and polystyrene;
(b) The hard anti-abrasive interconnecting layer is vacuum deposited and comprises a material of the general formula Mxe2x80x94Oxe2x80x94Cxe2x80x94Hxe2x80x94N (wherein M is preferably selected from the group consisting of silicon, titanium, tantalum, germanium, boron, zirconium, aluminum, hafnium and yttrium);
(c) the hard antiabrasive interconnecting layer is at least a monolayer thick (e.g., up to 10 microns thick);
(d) the lubricious hydrophobic coating layer is from about 1 to about 500 Angstroms thick;
(e) the organic lubricant comprises a perfluoropolyether; and
(f) the wear-resistant surface has a Bayer Index of at least about 5.
A method of making a substantially optically transparent articles as described above comprises the steps of:
(a) providing a substantially optically transparent polymeric substrate having a surface portion;
(b) depositing a hard antiabrasive interconnecting layer on the surface portion, preferably by vacuum deposition; and then
(c) bonding a lubricious hydrophobic coating layer to the interconnecting layer so that the hard antiabrasive interconnecting layer and the lubricious hydrophobic coating layer together forming the wear-resistant surface. The lubricious hydrophobic coating layer preferably comprises a hydrophobic organic lubricant selected from the group consisting of fluorocarbons, fatty acids, and fatty acid esters.